Exclusive Chicago Fire Sneak Peek: Casey Makes a Startling Discovery

After weeks of having to deal with the physical and emotional side effects of his near-fatal head trauma, it looks Lt. Casey (Jesse Spencer) is finally getting back to his A-game on Chicago Fire.

In this exclusive sneak peek from Tuesday's new episode (10/9c, NBC), Casey makes a surprising, and possibly life-altering, discovery when he and the team are tasked with trying to locate five victims in a huge apartment building blaze.